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Energy‐variable collision‐induced dissociation study of 1,3,5‐trisubstituted 2‐pyrazolines by electrospray mass spectrometry
Author(s) -
Kéki Sándor,
Nagy Lajos,
Török János,
Tóth Katalin,
Lévai Albert,
Zsuga Miklós
Publication year - 2007
Publication title -
rapid communications in mass spectrometry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.528
H-Index - 136
eISSN - 1097-0231
pISSN - 0951-4198
DOI - 10.1002/rcm.3029
Subject(s) - chemistry , fragmentation (computing) , collision induced dissociation , pyrazoline , dissociation (chemistry) , ion , mass spectrometry , aziridine , substituent , tandem mass spectrometry , medicinal chemistry , computational chemistry , organic chemistry , chromatography , ring (chemistry) , computer science , operating system
The pathways of the ([M+H] + ) ions generated from electrosprayed solutions of nine 1,3,5‐trisubstituted 2‐pyrazoline derivatives were studied using energy‐variable collision‐induced dissociation (CID) and pseudo‐MS 3 (in‐source CID combined with MS/MS) methods. It was shown that under CID conditions several structurally important product ions such as the 2,4‐substituted azete and 1,2‐substituted aziridine ions were formed. The compositions of the product ions were unambiguously supported by accurate mass measurement (mass accuracy was within ± 8 ppm). The fragmentation pathways of 1,3,5‐trisubstituted 2‐pyrazolines were established by means of pseudo‐MS 3 . It was found that a substituent at the N‐1 position greatly affects the fragmentation pathways of the 2‐pyrazoline derivatives. The 1‐acetyl‐ and 1‐propionyl‐2‐pyrazoline derivatives dissociate mainly through formation of a pyrazolium cation, while in the case of 1‐phenyl‐2‐pyrazoline derivatives product ions arising from the consecutive fragmentation of 2,4‐substituted azete and 1,2‐substituted aziridine ions dominate. Another interesting finding is the formation of a radical cation from the 2,4‐substituted azete by loss of a methyl radical. The fragmentation yield as a function of the collision energy for each of the 1,3,5‐trisubstituted 2‐pyrazolines was determined. Based on the fragmentation yield versus collision energy curves the relative fragmentation stabilities for the 1,3,5‐trisubstituted 2‐pyrazoline derivatives were also evaluated. Copyright © 2007 John Wiley & Sons, Ltd.